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If an electron in an hydrogen atom jumps from an orbit ni=3 to an orbit with level nf=2, the frequency of the emitted radiation is 

1. v=36 C5 R 

2. v = CR6

3. v = 5 RC36

4. v  = 6 CR

Subtopic:  Bohr's Model of Atom |
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The wavenumber of a photon in the Brackett series of a hydrogen atom is 9400R. What is the quantum number of the electron that has transited from the orbit?
1. 5
2. 6
3. 4
4. 7

Subtopic:  Spectral Series |
 65%
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In an experiment to determine the e/m value for an electron using Thomson's method the electrostatic deflection plates were 0.01 m apart and had a potential difference of 200 volts applied. Then the electric field strength between the plates is 

1. 1×104 V/m 

2. 2×104 V/m

3. 4×104 V/m 

4. 5×105 V/m

Subtopic:  Various Atomic Models |
 87%
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Hydrogen 1H1, Deuterium 1H2, singly ionised helium (2He4)+, and doubly ionised lithium(3Li6)+++ all have one electron around the nucleus. Consider an electron transition from n=2 to n=1. If the wavelengths of emitted radiations are λ1,λ2,λ3 and λ4 respectively, then approximately which one of the following is correct?
1. 4λ1=2λ2=2λ3=λ4
2. λ1=2λ2=2λ3=λ4
3. λ1=λ2=4λ3=9λ4
4. λ1=2λ2=3λ3=λ4

Subtopic:  Bohr's Model of Atom |
 80%
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To explain his theory, Bohr used

1. conservation of linear momentum

2. conservation of angular momentum

3. conservation of quantum  frequency

4. conservation of energy

Subtopic:  Bohr's Model of Atom |
 86%
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Bragg's law for X-rays is:

1. dsinθ = 2nλ 

2. 2dsinθ = nλ

3. nsinθ = 2λd

4. None of these

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The minimum wavelength of X-rays produced by electrons accelerated by a potential difference of V volt is equal to 

1. eVhc 

2. ehcV 

3. hceV 

4. cVeh

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The graph between the square root of the frequency of a specific line of the characteristic spectrum of X-rays and the atomic number of the target will be:

1.   
2.    
3. 
4.   
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The wavelength of Kα X-rays for lead isotopes Pb208, Pb206, Pb204 are λ1, λ2 and λ3 respectively. Then

1. λ1=λ2>λ3   

2. λ1>λ2>λ3

3. λ1<λ2<λ3 

4. λ2=λ1=λ3

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which of the following is positively charged?

1.  α-particles  

2.  β-particles  

3.  γ-rays  

4.  X-rays

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